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Figure 157: Wind profiles observed for different stability classes at Høvsøre, Denmark. The
markers indicate the combined lidar/cup anemometer observations, the solid lines the predictions
using Eqs. (261) and (262) with d = 5/4, and the dashed lines the predictions from Eq.
(250). Legend as in Fig. 153.
Once η and zi are estimated, the wind speed observations can be compared to the models.
Figure 157 illustrates the comparison of the models in Eqs. (261) and (262) with d = 5/4,
the surface-layer wind profile, Eq. (250), and the wind speed observations for the number of
stability classes also used in Figures 153 and 154. As with the neutral observations, surfacelayer
scaling fits well the observations within the surface layer only. The wind profile model,
which limits the value of the length scale, corrects for the departures of the observations
beyond the surface layer. Similar results were obtained in Peña et al. (2010a) using Eqs.
(261) and (262) with d = 1 and the wind profile models in Gryning et al. (2007).
11.4 Summary
• Theuseofground-basedremotesensinginstrumentshasbeenusefulforthestudyanddescription
of the wind profile within and beyond the surface layer and for the improvement
of the models that are traditionally used in wind power and boundary-layer meteorology.
• Over flat land and homogenous terrain and over the sea, the surface-layer wind profile
fits well the observations for a wide range of atmospheric stability conditions within the
surface layer only. For the analysis of wind profiles over water, however, a new scaling
should be added in order to account for the variable roughness length.
• Wind speed observations from combined lidar/cup anemometer measurements up to 160
m AMSL at the Horns Rev offshore wind farm are well predicted by wind profile models
that limit the value of the length scale, as suggested by Gryning et al. (2007), where the
BLH becomes an important parameter, particularly for stable conditions.
• Near-neutral wind speed observations from combined lidar/cup anemometer measurements
up to 300 m AGL at Høvsøre, Denmark, departure from the logarithmic wind
profile beyond the surface layer. Simple analytical models, which limit the value of the
length scale, predict such departure and fit well the observations.
• Wind profile models, extended for diabatic conditions, are compared to wind speed observations
from combined lidar/cup anemometer measurements up to 300 m AGL at
Høvsøre, Denmark, for a number of stability conditions. The models, which also limit
228 DTU Wind Energy-E-Report-0029(EN)
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